Make sure that you update your MSI X99S XPOWER AC motherboard to firmware 1.8 or newer for full compatibility. In the BIOS – set your “M.2 Source Link” to “Auto” and your “M.2 PCH Strap” to “M.2 PCH PCIE” for full x4 speeds (verify using Samsung Magician – as shown in the above image). I used Samsung’s Data Migration software to move from my Samsung 850 PRO 256GB SSD and it worked flawlessly.